bisect--helper: rewrite `check_term_format` shell function in C

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index b6ee0acb82765000a96795e7fb9f7f46b53f841f..db9091e249454e2678ce37fb7c5c5b391e330bcc 100644 (file)
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -2,19 +2,73 @@
 #include "cache.h"
 #include "parse-options.h"
 #include "bisect.h"
+#include "refs.h"
 
 static const char * const git_bisect_helper_usage[] = {
        N_("git bisect--helper --next-all [--no-checkout]"),
+       N_("git bisect--helper --check-term-format <term> <orig_term>"),
        NULL
 };
 
+/*
+ * Check whether the string `term` belongs to the set of strings
+ * included in the variable arguments.
+ */
+LAST_ARG_MUST_BE_NULL
+static int one_of(const char *term, ...)
+{
+       int res = 0;
+       va_list matches;
+       const char *match;
+
+       va_start(matches, term);
+       while (!res && (match = va_arg(matches, const char *)))
+               res = !strcmp(term, match);
+       va_end(matches);
+
+       return res;
+}
+
+static int check_term_format(const char *term, const char *orig_term)
+{
+       int res;
+       char *new_term = xstrfmt("refs/bisect/%s", term);
+
+       res = check_refname_format(new_term, 0);
+       free(new_term);
+
+       if (res)
+               return error(_("'%s' is not a valid term"), term);
+
+       if (one_of(term, "help", "start", "skip", "next", "reset",
+                       "visualize", "replay", "log", "run", "terms", NULL))
+               return error(_("can't use the builtin command '%s' as a term"), term);
+
+       /*
+        * In theory, nothing prevents swapping completely good and bad,
+        * but this situation could be confusing and hasn't been tested
+        * enough. Forbid it for now.
+        */
+
+       if ((strcmp(orig_term, "bad") && one_of(term, "bad", "new", NULL)) ||
+                (strcmp(orig_term, "good") && one_of(term, "good", "old", NULL)))
+               return error(_("can't change the meaning of the term '%s'"), term);
+
+       return 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
-       enum { NEXT_ALL = 1 } cmdmode = 0;
+       enum {
+               NEXT_ALL = 1,
+               CHECK_TERM_FMT
+       } cmdmode = 0;
        int no_checkout = 0;
        struct option options[] = {
                OPT_CMDMODE(0, "next-all", &cmdmode,
                         N_("perform 'git bisect next'"), NEXT_ALL),
+               OPT_CMDMODE(0, "check-term-format", &cmdmode,
+                        N_("check format of the term"), CHECK_TERM_FMT),
                OPT_BOOL(0, "no-checkout", &no_checkout,
                         N_("update BISECT_HEAD instead of checking out the current commit")),
                OPT_END()
@@ -29,6 +83,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
        switch (cmdmode) {
        case NEXT_ALL:
                return bisect_next_all(prefix, no_checkout);
+       case CHECK_TERM_FMT:
+               if (argc != 2)
+                       return error(_("--check-term-format requires two arguments"));
+               return check_term_format(argv[0], argv[1]);
        default:
                return error("BUG: unknown subcommand '%d'", cmdmode);
        }